Hitherto, as a method of performing ink jet printing with aqueous ink on a printing base material through use of an ink jet printer, there has been proposed a method of performing printing while heating the printing base material being conveyed (Patent Document 1).
As a method of heating the printing base material being conveyed as described above, there has been employed a method of heating a back surface of the printing base material through use of a hot plate or the like.
However, even when the back surface of the printing base material is heated through use of the hot plate or the like, there arises the following problem in a case of performing printing while continuously conveying the printing base material. That is, when a printing speed reaches a speed of about 15 m/min, ink flow and color blurring caused by insufficient drying of ink and the like, color mixing during multicolor printing, and the like occur. In particular, when white color is printed, there is a problem in that a larger amount of ink is required as compared to other colors, and hence the ink is not dried easily.
Further, as methods of performing printing while continuously conveying the printing base material, there are given a scan system and a single-pass system. Of those systems, the single-pass system is more suitable for high-speed printing because the single-pass system does not require scanning. A single-pass system ink jet recording method is disclosed, for example, in Patent Document 2. However, as described above, there is a problem in that, when the printing speed reaches a speed of about 15 m/min, ink flow and color blurring caused by insufficient drying of ink and the like, color mixing during multicolor printing, and the like occur. In particular, when white color is printed, there is a problem in that a larger amount of ink is required as compared to other colors, and hence the ink is not dried easily, with the result that the printing speed cannot be increased easily.
Meanwhile, as methods of performing printing on a web-shaped printing base material by a single-pass system, there are given back-surface printing and front-surface printing depending on the application.
When printing is performed on a transparent web-shaped printing base material, such as a web-shaped synthetic resin film, the back-surface printing is suitable. In the case of the back-surface printing, white color (W) is printed on a printing surface side after printing of each color (black (K), cyan (C), magenta (M), yellow (Y), and the like) is performed.
When printing is performed on an opaque web-shaped printing base material, such as web-shaped paper or non-woven fabric, the front-surface printing is performed. In the case of the front-surface printing, printing of each color (black (K), cyan (C), magenta (M), yellow (Y), and the like) is performed after white color (W) is printed on a printing surface side.
In the related art, an ink jet printer dedicated to the back-surface printing, which is configured to perform the back-surface printing on a web-shaped printing base material by a single-pass system, and an ink jet printer dedicated to the front-surface printing, which is configured to perform the front-surface printing on a web-shaped printing base material by a single-pass system, are separately prepared, and the back-surface printing and the front-surface printing are performed by the ink jet printers, respectively.
However, when the ink jet printer dedicated to the back-surface printing and the ink jet printer dedicated to the front-surface printing, which is configured to perform the front-surface printing, are separately prepared, facility cost and installation areas are required correspondingly. Therefore, there has been a demand for the emergence of an ink jet printer capable of performing the back-surface printing and the front-surface printing on a web-shaped printing base material by a single-pass system.